8 draft-legg-ldap-binary-03.txt eB2Bcom
9 Intended Category: Standards Track 7 June 2005
13 Lightweight Directory Access Protocol (LDAP):
14 The Binary Encoding Option
16 Copyright (C) The Internet Society (2005). All Rights Reserved.
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23 aware will be disclosed, in accordance with Section 6 of BCP 79.
25 By submitting this Internet-draft, I accept the provisions of Section
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44 Technical discussion of this document should take place on the IETF
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46 <ietf-ldapbis@openldap.org>. Please send editorial comments directly
47 to the editor <steven.legg@eb2bcom.com>.
49 This Internet-Draft expires on 7 December 2005.
53 Each attribute stored in a Lightweight Directory Access Protocol
54 (LDAP) directory has a defined syntax (i.e., data type). A syntax
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60 INTERNET-DRAFT LDAP: The Binary Encoding Option June 7, 2005
63 definition specifies how attribute values conforming to the syntax
64 are normally represented when transferred in LDAP operations. This
65 representation is referred to as the LDAP-specific encoding to
66 distinguish it from other methods of encoding attribute values. This
67 document defines an attribute option, the binary option, which can be
68 used to specify that the associated attribute values are instead
69 encoded according to the Basic Encoding Rules (BER) used by X.500
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121 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
122 2. Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . 4
123 3. The binary Option. . . . . . . . . . . . . . . . . . . . . . . 4
124 4. Syntaxes Requiring Binary Transfer . . . . . . . . . . . . . . 4
125 5. Attributes Returned in a Search. . . . . . . . . . . . . . . . 5
126 6. All User Attributes. . . . . . . . . . . . . . . . . . . . . . 5
127 7. Conflicting Requests . . . . . . . . . . . . . . . . . . . . . 6
128 8. Security Considerations. . . . . . . . . . . . . . . . . . . . 6
129 9. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 6
130 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
131 10.1. Normative References. . . . . . . . . . . . . . . . . . 7
132 10.2. Informative References. . . . . . . . . . . . . . . . . 7
133 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8
134 Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 8
138 Each attribute stored in a Lightweight Directory Access Protocol
139 (LDAP) directory [ROADMAP] has a defined syntax (i.e., data type)
140 which constrains the structure and format of its values.
142 The description of each syntax [SYNTAX] specifies how attribute or
143 assertion values [MODELS] conforming to the syntax are normally
144 represented when transferred in LDAP operations [PROT]. This
145 representation is referred to as the LDAP-specific encoding to
146 distinguish it from other methods of encoding attribute values.
148 This document defines an attribute option, the binary option, which
149 can be used in an attribute description [MODELS] in an LDAP operation
150 to specify that the associated attribute values or assertion values
151 are, or are requested to be, encoded according to the Basic Encoding
152 Rules (BER) [BER] as used by X.500 [X.500] directories, instead of
153 the usual LDAP-specific encoding.
155 The binary option was originally defined in RFC 2251 [RFC2251]. The
156 LDAP technical specification [ROADMAP] has obsoleted the previously
157 defined LDAP technical specification [RFC3377], which included RFC
158 2251. However the binary option was not included in the newer LDAP
159 technical specification due to a lack of consistency in its
160 implementation. This document reintroduces the binary option.
161 However, except for the case of certain attribute syntaxes whose
162 values are required to BER encoded, no attempt is made here to
163 eliminate the known consistency problems. Rather the focus is on
164 capturing current behaviours. A more thorough solution is left for a
165 future specification.
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177 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
178 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
179 document are to be interpreted as described in BCP 14, RFC 2119
184 The binary option is indicated with the attribute option string
185 "binary" in an attribute description. Note that, like all attribute
186 options, the string representing the binary option is case
189 Where the binary option is present in an attribute description the
190 associated attribute values or assertion values MUST be BER encoded
191 (otherwise the values are encoded according to the LDAP-specific
192 encoding [SYNTAX] for the attribute's syntax). Note that it is
193 possible for a syntax to be defined such that its LDAP-specific
194 encoding is exactly the same as its BER encoding.
196 In terms of the protocol [PROT], the binary option specifies that the
197 contents octets of the associated AttributeValue or AssertionValue
198 OCTET STRING are a complete BER encoding of the relevant value.
200 The binary option is not a tagging option [MODELS] so the presence of
201 the binary option does not specify an attribute subtype. An
202 attribute description containing the binary option references exactly
203 the same attribute as the attribute description without the binary
204 option. The supertype/subtype relationships of attributes with
205 tagging options are not altered in any way by the presence or absence
206 of the binary option.
208 An attribute description SHALL be treated as unrecognized if it
209 contains the binary option and the syntax of the attribute does not
210 have an associated ASN.1 type [SYNTAX], or the BER encoding of values
211 of that type is not supported.
213 The presence or absence of the binary option only affects the
214 transfer of attribute and assertion values in protocol; servers store
215 any particular attribute value in a format of their choosing.
217 4. Syntaxes Requiring Binary Transfer
219 The attribute values of certain attribute syntaxes are defined
220 without an LDAP-specific encoding and are required to be transferred
221 in the BER encoded form. For the purposes of this document, these
222 syntaxes are said to have a binary transfer requirement. The
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231 Certificate, Certificate List, Certificate Pair and Supported
232 Algorithm syntaxes [PKI] are examples of syntaxes with a binary
233 transfer requirement. These syntaxes also have an additional
234 requirement that the exact BER encoding must be preserved. Note that
235 this is a property of the syntaxes themselves, and not a property of
238 5. Attributes Returned in a Search
240 An LDAP search request [PROT] contains a list of the attributes (the
241 requested attributes list) to be returned from each entry matching
242 the search filter. An attribute description in the requested
243 attributes list also implicitly requests all subtypes of the
244 attribute type in the attribute description, whether through
245 attribute subtyping or attribute tagging option subtyping [MODELS].
247 The requested attributes list MAY contain attribute descriptions with
248 the binary option, but MUST NOT contain two attribute descriptions
249 with the same attribute type and the same tagging options (even if
250 only one of them has the binary option). The binary option in an
251 attribute description in the requested attributes list implicitly
252 applies to all the subtypes of the attribute type in the attribute
253 description (however, see Section 7).
255 Attributes of a syntax with the binary transfer requirement, if
256 returned, SHALL be returned in the binary form, i.e., with the binary
257 option in the attribute description and the associated attribute
258 values BER encoded, regardless of whether the binary option was
259 present in the request (for the attribute or for one of its
262 Attributes of a syntax without the binary transfer requirement, if
263 returned, SHOULD be returned in the form explicitly requested. That
264 is, if the attribute description in the requested attributes list
265 contains the binary option then the corresponding attribute in the
266 result SHOULD be in the binary form. If the attribute description in
267 the request does not contain the binary option then the corresponding
268 attribute in the result SHOULD NOT be in the binary form. A server
269 MAY omit an attribute from the result if it does not support the
272 Regardless of the encoding chosen, a particular attribute value is
273 returned at most once.
275 6. All User Attributes
277 If the list of attributes in a search request is empty, or contains
278 the special attribute description string "*", then all user
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287 attributes are requested to be returned.
289 Attributes of a syntax with the binary transfer requirement, if
290 returned, SHALL be returned in the binary form.
292 Attributes of a syntax without the binary transfer requirement and
293 having a defined LDAP-specific encoding SHOULD NOT be returned in the
296 Attributes of a syntax without the binary transfer requirement and
297 without a defined LDAP-specific encoding may be returned in the
298 binary form or omitted from the result.
300 7. Conflicting Requests
302 A particular attribute could be explicitly requested by an attribute
303 description and/or implicitly requested by the attribute descriptions
304 of one or more of its supertypes, or by the special attribute
305 description string "*". If the binary option is not present in all
306 these attribute descriptions, nor absent in all these attribute
307 descriptions, then the effect of the request with respect to binary
308 transfer is implementation defined.
310 8. Security Considerations
312 When interpreting security-sensitive fields, and in particular fields
313 used to grant or deny access, implementations MUST ensure that any
314 matching rule comparisons are done on the underlying abstract value,
315 regardless of the particular encoding used.
317 9. IANA Considerations
319 The Internet Assigned Numbers Authority (IANA) is requested to update
320 the LDAP attribute description option registry [BCP64] as indicated
321 by the following template:
324 Request for LDAP Attribute Description Option Registration
326 Family of Options: NO
327 Person & email address to contact for further information:
328 Steven Legg <steven.legg@eb2bcom.com>
329 Specification: RFC XXXX
330 Author/Change Controller: IESG
331 Comments: The existing registration for "binary"
332 should be updated to refer to RFC XXXX.
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343 10.1. Normative References
345 [KEYWORD] Bradner, S., "Key words for use in RFCs to Indicate
346 Requirement Levels", BCP 14, RFC 2119, March 1997.
348 [BCP64] Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
349 Considerations for the Lightweight Directory Access
350 Protcol (LDAP)", BCP 64, RFC 3383, September 2002.
352 [ROADMAP] Zeilenga, K., "Lightweight Directory Access Protocol
353 (LDAP): Technical Specification Road Map",
354 draft-ietf-ldapbis-roadmap-xx.txt, a work in progress,
357 [MODELS] Zeilenga, K., "LDAP: Directory Information Models",
358 draft-ietf-ldapbis-models-xx.txt, a work in progress,
361 [PROT] Sermersheim, J., "LDAP: The Protocol",
362 draft-ietf-ldapbis-protocol-xx.txt, a work in progress,
365 [SYNTAX] Legg, S. and K. Dally, "Lightweight Directory Access
366 Protocol (LDAP): Syntaxes and Matching Rules",
367 draft-ietf-ldapbis-syntaxes-xx.txt, a work in progress,
370 [PKI] Zeilenga, Kurt D., "Lightweight Directory Access Protocol
371 (LDAP) schema definitions for X.509 Certificates",
372 draft-zeilenga-ldap-x509-xx.txt, a work in progress,
375 [BER] ITU-T Recommendation X.690 (07/02) | ISO/IEC 8825-1,
376 Information Technology - ASN.1 encoding rules:
377 Specification of Basic Encoding Rules (BER), Canonical
378 Encoding Rules (CER) and Distinguished Encoding Rules
381 10.2. Informative References
383 [RFC2251] Wahl, M., Howes, T. and S. Kille, "Lightweight Directory
384 Access Protocol (v3)", RFC 2251, December 1997.
386 [RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access
387 Protocol (v3): Technical Specification", RFC 3377,
390 [X.500] ITU-T Recommendation X.500 (1993) | ISO/IEC 9594-1:1994,
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399 "Information Technology - Open Systems Interconnection -
400 The Directory: Overview of concepts, models and services".
406 Suite 3, Woodhouse Corporate Centre
408 Box Hill North, Victoria 3129
411 Phone: +61 3 9896 7830
413 EMail: steven.legg@eb2bcom.com
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